A second unit configured to be opened or closed with respect to a first unit includes a background plate configured to be switched between a facing state in which the background plate faces a image sensor and a non-facing state in which the facing state of the background plate and the image sensor is released and a power receiving section configured to receive power from a motor to switch the state of the background plate. The first unit includes an intermediate cam configured to be rotated by the power from a motor and a cam member configured to receive the power of the motor via the intermediate cam, the cam member having a receiving section of a size the power receiving section is received regardless of a position of the power receiving section when the intermediate cam is in the neutral position.